Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high pressure air and is ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft. Left-over products of the combustion are exhausted out of the turbine and may provide thrust in some applications.
Air is drawn into the engine through an air intake and communicated to the compressor via an air-intake duct. In some operating conditions, particles may be entrained in the air such as dirt, dust, sand, or liquid and may be drawn into the air intake and passed through the air-intake duct to the compressor. Such particles may impact components of the compressor and turbine causing unintended wear. In addition, the deposit and accumulation of particles may cause fowling and plugging of engine passages. This unintended wear may decrease power output of the engine, shorten the life span of the engine, and lead to increased maintenance costs and increased down time of the engine.
To separate particles from air entering the compressor, an inertial particle separator may be utilized. The inertial particle separator uses the inertia of the particles to separate the particles from the air. As the air stream moves through the air-intake duct, the air moves along a serpentine flow path and enters a compressor passage of the air-intake duct while the particles move along a generally linear travel path and enter a scavenge passage included in the air-intake duct. In some instances, particles may deviate from the generally linear travel path and enter the compressor passage rather than the scavenge passage. Particles may deviate from the generally linear travel path due separation of flow from an outer wall of the air-intake duct leading to recirculation of the particles and/or other fluid flow phenomenon upstream of the scavenge passage.
Traditional technologies for particle separation may include a vortex tube and a barrier filter. The vortex tube requires a swirl tube structure, which unnecessarily consumes space and weight. The barrier filter uses a media to capture particulate, but requires frequent cleaning maintenance. Furthermore, inertial particle separators may utilize inflatable boots. However, these inflatable flow surfaces merely constrict or obstruct flow and do not contain translating components for enhanced particle separation. Thus, the capabilities of traditional particle separators are limited.
With traditional technologies, transient flow structures may be generated within an internal boundary layer separated flow region. This may sporadically extend the influence of the disturbed flow beyond the time averaged flow behaviors and locally interrupt the flow into the scavenge passage. This interruption may be to the extent of allowing a portion of the air that has entered the scavenge passage, that is laden with particulate, to enter the leg of the particle separator intended for compressor flow only. Traditional technologies have limited ability to minimize the formation of transient flow structures or the negative resulting influences on engine performance.
In addition, traditional technologies do not have sufficient ability to adjust or adapt the operation and performance characteristics of the particle separator to the demands placed on the turbine engine due to changing engine power demands, engine degradation level, or dramatically changing quantity or properties of particulate entering the engine inlet system. In many cases this causes the particle separator system to adversely affect the engine performance even in the absence of the presence of particulate.
To address the above, there is a need for an adaptive particle separation system. The need is to reduce the penalties to engine operation caused by the particle separator in when the operational environment causes them to be unneeded or inappropriate. It may be desirable to provide adaptive features such as sensors, active control devices, electrostatics, translating components, and variable control of scavenge passage flow level. Thus, there is a need for a system that minimizes the total penalties that the separator imposes on the gas turbine engine while also realizing an appropriate level of protection of the engine from sand and dust as it is present in the inlet airstream.